Comprehensive analysis of surface roughness for extremely high frequency antennas

Antennas suitable for 6 G applications can potentially operate in the W-band (75–110 GHz), which requires fine manufacturing accuracy, particularly for fine surface processing. Such antennas with fine surfaces can be produced using many different techniques, such as chemical etching, milling, and additive manufacturing. However, even fine manufacturing leads to certain imperfections on the antenna surface that lead to the performance degradation of an antenna. As a result, an undesirable difference between the numerical and experimental results can occur. To study this effect, we performed electromagnetic simulations of surface roughness in multiple conventional electromagnetic devices suitable for 6 G applications. As antennas under investigation, we have chosen a horn antenna and a patch antenna. In addition, we consider a rectangular WR-10 waveguide and a 50 Ohm microstrip transmission line. Surface roughness has been implemented as a set of hemispheres, which are randomly distributed, added, or subtracted on the surface of the antenna. After performing a set of simulations, we evaluated the S-parameters, antenna efficiency, and directivity patterns. The results are then compared with reference devices with ideal surfaces to find the optimal surface requirement for antenna manufacturing.